I'm sure you'll be just fine. Yeah, the rack mounting feet may seem a bit concerning, but remember there are 4 mounts per side. That means there's only a little over 26 lbs being held up by each of the mounting feet. That's not bad at all. Per US Rack's website, the load rating for one crossbar is 125 lbs. That gives an overall dynamic load rating of 250 lbs. You're 40 lbs under that limit with only the RTT, so I think that's a pretty darn safe margin for error. Even with some sleeping stuff up there you're still within the load limits. Heavy offroading will put more stress on it, but according to their test results, the rack didn't bend until about 600 lbs of force was applied. I think you'll be pretty safe.
Static loads will be fine too. Less movement, less stress, and the RT ladder is supporting a huge chunk of the weight.